If you or your child was born with a birthmark, you may have a lot of questions you'd like to ask a dermatologist.

One type of vascular birthmark is called a congenital hemangioma. It is a rare, noncancerous tumor made up of thickened skin and many thin-walled blood vessels that is present and fully grown at birth. Another kind of birthmark is called a vascular malformation. It is a collection of blood vessels and is often present at birth.

"Our doctors regularly see patients with birthmarks and have vast experience identifying them," says Richard J. Antaya, MD, a Yale Medicine pediatric dermatologist.

Our Yale Medicine physicians are internationally recognized leaders in vascular birthmark research, studying hemangioma for more than 20 years.

Congenital hemangiomas are present at birth and do not grow after the baby is born.

Congenital hemangiomas are not cancerous and are not dangerous. Here are the two main kinds of congenital hemangiomas:

• Rapidly involuting congenital hemangiomas, which look like purplish nodules and go away very quickly, starting to shrink within the first few months of life and usually disappearing within the first year.
• Non-involuting congenital hemangiomas, which never shrink or go away. They look like venous malformations— often a dark blue color, and soft—and tend to be very stagnant. Similarly, there are also partially involuting congenital hemangiomas (PICH), which shrink a little but then never really go away completely.

Like congenital hemangiomas, vascular malformations, are also called birthmarks. However, vascular malformations are made of abnormally formed blood vessels and are nearly always present at birth. They may grow in proportion with the patient but some grow faster. Vascular malformations don’t shrink like rapidly involuting congenital hemangioma (or infantile hemangiomas) do. The five major types of vascular malformations are:

• Port wine stains or capillary malformations (flat pink, red, or purple spots)
• Venous malformations (uneven areas of skin, darker blue and soft)
• Lymphatic malformations (made of the lymph vessels)
• Arteriovenous malformations (arteries connecting directly to veins without capillaries between the two).
• Mixed malformations (combinations of any of the above types of birthmarks). 

If a malformation is not present at birth and/or it increases or decreases in size, it is called a vascular neoplasm.

Scientists are researching the causes hemangiomas and vascular malformations, which are largely unknown and occur during development. The conditions have nothing to do with what the baby’s mother ate or drank (or didn’t consume) during pregnancy.

While most often birthmarks aren't harmful to a baby or child, parents are concerned about disfigurement, especially if the malformation is on the head or neck area.

In some cases, however, large venous malformations can put patients at risk for blood clots, bleeding or heart issues which is why you should always have birthmarks evaluated by a physician.

Doctors may diagnose a congenital hemangioma through prenatal ultrasound. If the condition is not detected at that stage, it will be obvious as a skin lesion immediately after birth. All birthmarks require physician evaluation to obtain an accurate diagnosis and, if necessary, deliver any treatments.

Most rapidly involuting congenital hemangiomas can be diagnosed by a physical exam and observation over a few months. Doctors may also use a range of diagnostic tools, depending on the type, size, and location of the birthmark. A comprehensive evaluation may include blood tests, biopsy, ultrasound, magnetic resonance imaging (MRI) and angiogram. Depending on which organ systems are potentially involved by the hemangioma or malformation, different specialists may get involved in treatment.

For certain vascular malformations, specifically capillary malformations (port wine stains), there is some data that suggests that treating infants is more effective than waiting until they are older.

Doctors at Yale Medicine will begin laser treatments in infants as early as three to four weeks of age to help lighten the color of port wine stains. The laser damages the abnormally formed vessels in the skin which subsequently decreases the red color.

Occasionally, doctors at Yale Medicine employ a topical medicine, sirolimus cream, to the area after laser treatment to prevent the regrowth of the blood vessels. If a child has an arterial or venous malformation, the doctor might administer injections to damage and/or shrink the vessels. Sometimes patients might receive a combination of laser therapy, injections and/or topical medications.

Our scientists and physicians who work on vascular malformation research have been studying these conditions for more than two decades. “We have performed research on hemangiomas as well as research in educating parents about these birthmarks over the years, and I think it shows,” Dr. Antaya says.

“When there are new treatment options out there, we are evaluating them and trying to improve patient care,” he says.

Throughout treatment, the specialists at Yale Medicine also work closely with referring doctors, keeping them informed and working with them to track how patients do during and after care.